Sealing connections, such as are used for sealing covers, flange pipe connections and the like, may be made by various methods. For example, the covers or flanges may be cast and have their peripheries machined to provide a flat sealing surface which engages a gasket to seal an opening or the periphery of an associated connection. Alternatively a seal groove for a resilient O-ring seal or its equivalent may be machined in the surface to seal the joint. Covers and flanges may also be made by cutting them from steel plate, or the like, thick enough to provide a stiff sealing connection, in combination with a gasket or an O-ring seal disposed in a machined groove.